hitpighead.java

《java游戏设计》范例源代码及程序执行结果

// 程序：游戏开头画面
// 范例文件：HitPigHead.java

import java.awt.*;
import java.util.*;     //为了使用其中的Random类
import java.applet.*;

class StartScreen       //开始画面类
{
   //=====资料成员==================================================
   int     width,height,StringWidth,StringHeight,Ascent,Descent,X,Y;
   int     ImageLeftBound,ImageRightBound,ImageX,ImageY,ImageWidth,
           ImageHeight,VX;
   Font    F1,F2,F3;
   Image   Normal,bkImage,Hit,currentImage;
   String  ChineseTitle,EnglishTitle,PressEnter;
   HitPigHead  Game;
   Random  R;
   boolean showPressEnter;

   FontMetrics FM;

   //=====函数成员==================================================
   public StartScreen(int AppletWidth,int AppletHeight,HitPigHead Game,
                      Image normal,Image hit, Image bk)
   {
      R      = new Random();     //用来取随机数的类  

      //绘制字符串需要用到的三种字型
      F1     = new Font("TimesRoman",Font.BOLD,72);
      F2     = new Font("TimesRoman",Font.BOLD + Font.ITALIC,36);
      F3     = new Font("TimesRoman",Font.BOLD,20);

      ChineseTitle    = "棒打猪头";                      //使用F1
      EnglishTitle    = "Hit Pig's Head";                //使用F2
      PressEnter      = "<<<==请按Enter键开始游戏==>>>"; //使用F3

       width           = AppletWidth;                     //Applet的宽度
      height          = AppletHeight;                    //Applet的高度

      Normal          = normal;  //小猪图像1
      Hit             = hit;     //小猪图像2
      bkImage         = bk;      //背景图像
 
      ImageWidth      = Normal.getWidth(Game);    //小猪图像的宽度
      ImageHeight     = Normal.getHeight(Game);   //小猪图像的高度
      ImageLeftBound  = 25;                       //小猪图像移动的左边界
      ImageRightBound = AppletWidth - (25 + ImageWidth);        //右边界 
      ImageX          = ImageRightBound;          //小猪图像的起始位置 
 
      VX              = -3;      //图像移动的速度
      this.Game       = Game;
      currentImage    = Normal;  //指定目前图像为小猪图像1
      showPressEnter  = true;    //显示PressEnter字符串
   }

   public void UpdateStatus()       //更新动画状态的函数
   {
      ImageX = ImageX + VX;         //指定图像的新位置

      if(ImageX <= ImageLeftBound)  //如果碰到左边界的话 
      {
         currentImage = Hit;        //指定目前图像为小猪图像2

         ImageX = ImageLeftBound;   //设定图像的新位置
         VX     = -VX;              //改变图像移动方向
      }

      if(ImageX >= ImageRightBound) //如果碰到右边界的话
      {
         currentImage = Normal;     //指定目前图像为小猪图像1

         ImageX = ImageRightBound;  //设定图像的新位置
         VX     = -VX;              //改变图像移动方向
      }

      //利用随机数来让字符串闪动
      if(showPressEnter == true)
      {
         if((R.nextInt(5) + 1) % 5 == 0)
            showPressEnter = false;
      }
      else
      {
         if((R.nextInt(5) + 1) % 5 == 0)
            showPressEnter = true;
      }
   }

   public void paintScreen(Graphics g)   //绘制动画的函数
   {
      g.clearRect(0,0,width,height);     //清除次画面

      g.setFont(F1);                     //设定字型
      FM = g.getFontMetrics();

      Ascent       = FM.getAscent();
      Descent      = FM.getDescent();
      StringWidth  = FM.stringWidth(ChineseTitle);
      StringHeight = Ascent + Descent; 
      
      X            = (width - StringWidth) / 2;
      Y            = Ascent;
 
      g.drawImage(bkImage, 0, 0, Game);
      g.setColor(Color.white);           //设定前景色为白色
      g.drawString(ChineseTitle,X,Y);    //绘制中文标题

      Y            = StringHeight;
      g.drawLine(X,Y,X+StringWidth,Y);   //绘制线段1

      X            = X + 30;
      Y            = Y + 5;
      g.drawLine(X,Y,X+StringWidth-60,Y);//绘制线段2

      //===============================================================
      g.setFont(F2);                     //设定字型
      FM = g.getFontMetrics();

      Ascent       = FM.getAscent();
      Descent      = FM.getDescent();
      StringWidth  = FM.stringWidth(EnglishTitle);
      StringHeight = Ascent + Descent; 

      X            = (width - StringWidth) / 2;
      Y            = Y + Ascent;
      g.drawString(EnglishTitle,X,Y);    //绘制英文标题

      //===============================================================
      ImageY       = Y + Descent + 30; 
      g.drawImage(currentImage,ImageX,ImageY,Game);   //绘制小猪图像

      //===============================================================
      g.setFont(F3);                     //设定字型
      FM = g.getFontMetrics();

      Ascent       = FM.getAscent();
      Descent      = FM.getDescent();
      StringWidth  = FM.stringWidth(PressEnter);
      StringHeight = Ascent + Descent; 

      X            = (width - StringWidth) / 2;
      Y            = ImageY + ImageHeight + Ascent + 30;

      if(showPressEnter)
         g.drawString(PressEnter,X,Y);   //绘制PressEnter字符串
   }
}

public class HitPigHead extends Applet implements Runnable
{
   //=====资料成员==================================================
   int          AppletWidth,AppletHeight;
   Image        OffScreen,bkImage,PigHead_Normal,PigHead_Hit;
   Thread       newThread;
   Graphics     drawOffScreen;
   StartScreen  S_Screen;
   MediaTracker MT;

   //=====函数成员==================================================
   public void init()
   {
      setBackground(Color.black);        //设定背景颜色

      //加载小猪图像1和2(使用MediaTracker)与背景
      PigHead_Normal = getImage(getDocumentBase(),"Images/pig1.gif");
      PigHead_Hit    = getImage(getDocumentBase(),"Images/pig2.gif");
      bkImage        = getImage(getDocumentBase(),"Images/009.jpg");
      
      MT = new MediaTracker(this);
      MT.addImage(PigHead_Normal,0);
      MT.addImage(PigHead_Hit,0);

      try
      {
         showStatus("图像加载中(Loading Images)...");
         MT.waitForAll();
      }
      catch(InterruptedException E){ }   //没有进行例外处理

      AppletWidth  = getSize().width;    //取得Applet的高度
      AppletHeight = getSize().height;   //取得Applet的宽度

      //建立开始画面
      S_Screen = new StartScreen(AppletWidth,AppletHeight,this,
                 PigHead_Normal,PigHead_Hit, bkImage);
            
      //建立次画面
      OffScreen     = createImage(AppletWidth,AppletHeight);
      drawOffScreen = OffScreen.getGraphics();
   }

   public void start()                   //start()函数  
   {
       newThread = new Thread(this);      //建立与启动新线程
      newThread.start();
   }

   public void stop()                    //stop()函数
   {
      newThread = null;                  //将线程设为null
   }

   public void paint(Graphics g)
   {
      //如果图像下载发生任何错误的话...
      if((MT.statusAll(false) & MediaTracker.ERRORED)  != 0)
      {
         FontMetrics FM = g.getFontMetrics();

         int Ascent      = FM.getAscent();
         int Descent     = FM.getDescent();
         int StringWidth = FM.stringWidth("加载图像发生错误...");

         int X = (AppletWidth - StringWidth) / 2;
         int Y = (AppletHeight - (Ascent + Descent)) / 2 + Ascent;

         g.setColor(Color.white);                  //字符串设为白色 
         g.drawString("加载图像发生错误...",X,Y);  //置中显示字符串

         return;                                   //结束函数执行
      }   

      //将次画面的绘制工具输入以在次画面中绘制图像
      S_Screen.paintScreen(drawOffScreen);

      //将次画面贴到主画面中
      g.drawImage(OffScreen,0,0,this);
   }

   public void update(Graphics g)        //update()函数
   {
      paint(g);                          //只单纯调用paint()函数
   }
   
   public void run()
   {  
      while(newThread != null)           //动画循环
      {  
         repaint();                      //重新绘制图像

         try
         {
            Thread.sleep(80);            //暂停程序执行80毫秒
         }
         catch(InterruptedException E){ }//没有进行例外处理
       
         S_Screen.UpdateStatus();        //更新开始画面的动画状态
      }
   }
}